GNU and Unix systems are set up to allow many people to use the same computer, while keeping certain files private or keeping certain people from modifying certain files. You can verify this for yourself. Log in as yourself, i.e. NOT as root.
This verifies that you are not root. Then enter the following command:
You should be told Permission denied. /etc/resolv.conf is an essential system configuration file; you aren’t allowed to change or remove it unless you’re root. This keeps you from accidentally messing up the system, and if the computer is a public one (such as at an office or school), it keeps users from messing up the system on purpose.
Now type ls -l /etc/resolv.conf.
This will give you output that looks something like this:
The -l option to ls requests all that additional information. The info on the right is easy: The size of the file is 119 bytes; the date the file was last changed is February 23, 1997; and the file’s name is /etc/resolv.conf. On the left side of the screen, things are a little more complicated.
First, the brief, technical explanation: The -rw-r--r-- is the mode of the file, the 1 is the number of hard links to this file (or the number of files in a directory), and the two roots are the user and group owning the file, respectively.
So that was cryptic. Let’s go through it slowly.